Improvement in machines for cutting screw-taps



2Sheets--Sheet1. H. E. BOYD. Machines. for Cutting Screw-Taps.

Patented Oct, 26;1875' NFEI'ERS. PHOTD-LITHOGRAPHER, wAsuiNsr'ou, [1cv 2Sheets- SheeL2. H.'E BOYD. v Machines for Cutting Screw-Taps.

Patented Oct. 26, 1875.

" I v LR UNITED STATES PATENT Prices HENRY E. BOYD, OF MGKEESPORT, PENNSYLVANIA.

IMPROVEMENT IN MACHINES FOR CUTTING SCREW-TAPS.

Specification forming part of Letters Patent No. l69.080, dated October 26, 1875; application filed July 2 i, 1875.

To all whom it may concern:

Be it known that I, HENRY E. BOYD, of McKeesport, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Apparatus for Cutting Screw-Taps and internal threads of pipe and bolt dies; and I do hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawing, forming a part of this specification, in which Figure 1 is a plan view of an engine-lathe to which the devices embodying my invention have been applied. Fig. 2 is a perspective of the face-plate ot' head-stock, or the wormwheel and driving-gear, with the attachment for cutting the internal thread of pipe or bolt dies. Fig. 3 is a side elevation of the enginelathe and my devices attached there o. Fig. 4 is an enlarged sectional view of the driving spindle and the devices by which the change of speed is accomplished; and Figs. 5 and (-5 are views of a screw-tap and pipe or bolt dies.

Like letters refer to like parts wherever they occur.

My invention relates to the manufacture of screw-taps and pipe and bolt threading dies, and has for its object the construction of devices which may be applied to an engine-lathe when it is desired to cut the internal thread of a pipe or bolt die, and which can be readily removed when the lathe is to be employed either for cutting screw-taps or for its ordinary uses, and also to modify the construction of the driving-gear, by which the speed of the face-plate and blank is controlled, so that said gearing does not require to be removed from the lathe when not employed for its specific purpose, and does not impede the other uses of the lathe.

The invention consists, first, in combining with a face-plate of a lathe, having a ring or holder for securing a blank, mechanism for changing the speed of the face-plate and a cutting-tool for cutting the blank; and, second, in providing the hub of the speed-pulley with friction-blocks, and the hub of the slow pulley or gear wheel with spring-pawls, by means of which and a clutch and taper central spindle operated from the face-plate, the

speed will be automatically altered according to the work.

I will now proceed to describe my invention, so that others skilled in the art may make and use the same.

In the drawing, A is the frame of'the usual engine-lathe, having a headstock, B, provided with pulleys b, and imparting power to the feed-screw 0 through a series of intermediate cog-wheels, c. D is the tool-rest, which receives its motion from t'eedscrew U, and upon the rest is secured a revolving cutter, provided with a driving-pulley. The slide of the tool-post is connected by a link, d, to a rod, E, one end of which is provided with a movable eccentric connected by a spline-feather tothe rod, and jourualed in a bracket secured to the tail-stock. Thus the rod is provided with a bearing, central with the opposite end hearing, and one which, owing to the cure: tric sliding on the rod, enables the tail-stock of the lathe to be mov d up when turning small work. The opposite end of the rod E is connected with an universal joint, so as to center off the line of axis of said joint and ot' the hearing, whereby the rod E, when oscillated, acts as an eccentric. 0n the journal of rod E, next the face-plate, is an arm, which stands in the path of a cam upon the face-plate, so that at intervals the rod E is slightly rotated or oscillated, and thus draws forward the cutter at the time the blank is being out, so as to give the clearance or relief required in the thread of the tap or die. G indicates the face-plate ot' the lathe, toothed on its circumference to form a worm-wheel, which gears with the worm G. To the-face of G, Fig. 2, is secured a ring or similar holding device, g, provided with thumb or set screws g, the whole acting as a check or clutch to hold a pipe or bolt'die while the internal thread thereof is being cut. Thisring G'may be removed when not required for its specific purpose. H is a ta p-blank, supported between the centers of the head and tail stock, and clamped to the worm-wheel or face-plate G by" the usual dog h, which takes into a slot in the".

face-plate.

Upon the rear of the face-plate G, or' that, side of the faceplate next to the driving-pub" of the head-stock. the frame A, orto the head-stock, and is held itforward by a spring or similar device, 1 so 1 that a projection or cam, l upon it impinges leys, at regular intervals corresponding to the cuts to be made; on the hlauks,area series of cams or inclines, I, which actuate the shipping-lever of the driving-gear and the eccentric rod E, which brings the cutter up to its work. L is the shipping-lever, located between the rear side of the face-plate and the brackets, which support the driving-pulleys It is pivoted, as at l, to

against the rear of the face-plate, and at regular intervals engages with the face of one of a the cams I, which forces hack the lever, and changes the position of the clutch on the itdrivingshaft. At the same timethat the face of cam I actuates lever L, the side of cam I engages with an arm, secured to the endof eccentric rod E, oscillating or slightly rotating therod in such a manner as to force in the frame A, said worm gearing with the toothed face plate, and by nieansof beveled cogwheelsk k with a driving-shaft, which receives its power from the pulleys of the head-stock.

i M indicates the driving-shaft, through which the power is transmitted to the face-plate, with which the blank revolves, and, as the speed withwhich the blank is rotated is varied r at regular intervals, for the reasons before stated, Iconstruct this shaft and its pulleys as follows, with special reference thereto: The shattM is bored out for about twothirds of its length, for the reception of a tapered spindle, 'm,and is cut away at a, to seat a set of friction-blocks, 0, which are held in position by the hub of the speed-pulley O. The spindle m is secured to the sliding clutch N bya pin, which passes through a slot in the shalt M, so that the spindle moveswith the sliding clutch, and both the clutch and the spindle rotate with the shaft. 0 is the speed pulley or pulleys, which, in fact, is a tapered sleeveslipped upon shaft M, and which revolves loosely when not clutched to the shaft and thespeed-pulleys are running loose upon theshaft. The shaft Mis journaled in bracke tsl M",j attached to the frame A, or to the l ead-stock, and the speed pulleys are driven by belting from the pulleysof th'e head-stock,

but the slow motion is obtained through gearwheels r0" on shaft It, located between shaft M and thepulleys of the head'- stock, and

journaled in the same bracket as M. The pinion r may slide upon shaft R,'being held by a feather, s, or other suitable means, and i it will be apparent that by simply sliding the pinion 'rout of gear withP, and unshipping the belts from the speed-pulleys, the headstock will be freed from the remaining driving-gear, and the lathe may be used in the usual manner without the removal of any devices, except those employed ,to secure the pipe or bolt-die to the face-plate. Fig. 3 shows pins upon the clutch, for griping the slow pulley, whichare we1l known devices for clutching the pulleys, and may be substituted for the spring-dogs p of P. The operation of these devices is as follows When cutting a tap the die-rin g g may beleftupi on the face-plate,or'removed therefrom,aspreferred. It is not in the way, but performs no function. The tap-blank previously grooved lon gitudinally is secured between the centers oi ,1

the head and tail stock, Fig. 1, and power maps the slowpulley, and the speed ofthefaceplate is decreased during thecutt-ing. Attire/7f" same time that carnlengages withleverL the side of the cam actuates an armattached I to eccentric rod E, and oscillatesuor slightly rotates eccentric rod E, whichhriiigs forward the tool-carriage and cutter. a As soon as the cam I passes the arm of E and the projection l of L, the lever and eccentric rod are brought back to their first position by springsbr other suitable devices, the lever L again sliding the I clutch N on shaft M, so as to throw the slow a pinion or pulley out of gear, and drawing for-Q ward the taper spindle m, which motion is as- I sisted by a spring, t, acting on the end of the spindle, so as to force out the friction-blocks 0, and thus clutch the speed pulley, which again revolves the face-plate rapidly until an; other cam, I, strikes lever L. a The reverse ro-l has, in the meanwhile, withdrawn thecutter. These several operations of the machine are] repeated until the tap is fully cut,thetoolrest being fed along the framebythe feeda screw in theusual manner,

When a pipe orbolt die isto be cut,

ringg is secured to the face-plate, and the Fig. 6, issecured within thering holderby and adjusted within the die on the side next to the worm, power is applied through shaft M, and the devices then operate as before specified in describing the cutting of the screwtap.

Amongthe advantages of these devices may be noted the ease, rapidity, and accuracy with which dies for pipe or bolts may be cut, and the compactness of the driving-gear, and devices for changing the speed of the face-plate, the construction of the latter being such that, if desired, they can be used with the lathe for other purposes than those specified, and when not in use they need not be detached-from the machine, as they do not interfere with the other uses to which an engine-lathe is applied.

Having thus described my invention, what I claim, and. desire to secure by Letters Patent, 1s

1. The combination of the face-plate, provided with a ring or holder for securing the blank, suitable mechanism for changing the speed of the face-plate, and the cutting-tool for cutting the blank, substantially as specified..

2. The combination of the loose pulley O, and friction-blocks with the hollow shaft, and tapered central spindle, substantially as and for the purpose specified.

3. The combination of the loose pulley P, or pinion having its hub provided with springpawls, the hollow shaft and tapered central spindle, and the loose pulley O, and frictionblocks.

In testimony whereof I, the said HENRY E. BOYD, have hereunto set my hand.

HENRY E. BOYD.

Witnesses:

F. W. BITTER, Jr., W. N. PAXTON. 

